netdev - Re: [PATCH net 1/2] gre: Fix IPv6 multicast route creation.

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Message-ID: <20250710135757.60581077@eugeo>
Date: Thu, 10 Jul 2025 13:57:57 +0100
From: Gary Guo <gary@...yguo.net>
To: Guillaume Nault <gnault@...hat.com>
Cc: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>,
 netdev@...r.kernel.org, Simon Horman <horms@...nel.org>, David Ahern
 <dsahern@...nel.org>, Ido Schimmel <idosch@...dia.com>, Aiden Yang
 <ling@...dove.com>
Subject: Re: [PATCH net 1/2] gre: Fix IPv6 multicast route creation.

On Wed, 9 Jul 2025 16:30:10 +0200
Guillaume Nault <gnault@...hat.com> wrote:

> Use addrconf_add_dev() instead of ipv6_find_idev() in
> addrconf_gre_config() so that we don't just get the inet6_dev, but also
> install the default ff00::/8 multicast route.
> 
> Before commit 3e6a0243ff00 ("gre: Fix again IPv6 link-local address
> generation."), the multicast route was created at the end of the
> function by addrconf_add_mroute(). But this code path is now only taken
> in one particular case (gre devices not bound to a local IP address and
> in EUI64 mode). For all other cases, the function exits early and
> addrconf_add_mroute() is not called anymore.
> 
> Using addrconf_add_dev() instead of ipv6_find_idev() in
> addrconf_gre_config(), fixes the problem as it will create the default
> multicast route for all gre devices. This also brings
> addrconf_gre_config() a bit closer to the normal netdevice IPv6
> configuration code (addrconf_dev_config()).
> 
> Fixes: 3e6a0243ff00 ("gre: Fix again IPv6 link-local address generation.")
> Reported-by: Aiden Yang <ling@...dove.com>
> Closes: https://lore.kernel.org/netdev/CANR=AhRM7YHHXVxJ4DmrTNMeuEOY87K2mLmo9KMed1JMr20p6g@mail.gmail.com/
> Reviewed-by: Gary Guo <gary@...yguo.net>
> Tested-by: Gary Guo <gary@...yguo.net>
> Signed-off-by: Guillaume Nault <gnault@...hat.com>

You probably also want to

Cc: stable@...r.kernel.org

so this gets picked up by the stable team after it's merged.

Best,
Gary